D. melanogasteras a model organism for the evaluation of possible health effects induce by occupational exposure to inhaled particulate matter

Particulate matter (PM) is one of the most harmful air pollutants and its presence has increased rapidly in recent decades with most emissions coming from road transport. Increasing attention has been paid to the non-exhaust component of PM, not deriving from direct combustion, but from mechanical processes such as brake and tire wear, as well as from dust resuspension. The growing awareness of the possible health impact of these pollutants has highlighted the needs of developing reliable and reproducible model systems to study their effects in vivo. D. melanogaster, capable of showing physiological and behavioral alterations like those of higher organisms, represent a suitable candidate. Therefore, the present work aims to propose the use of D. melanogaster as a model organism for the evaluation of possible health effects induced by occupational exposure to specific components of atmospheric particulate matter. Two different exposure scenarios were considered. In the first case, D. melanogaster larvae were developed on a growth medium containing scalar concentrations of brake dust, a component of the non-exhaust portion of PM, potentially dangerous for human health. Upon completion of the metamorphosis phase, the resulting adult individuals were frozen in liquid nitrogen and subjected to metabolomic analysis by NMR spectroscopy. In the second case, adult individuals were exposed to five different sites within a foundry (representative of a specific phase of the production process) and subjected to the same analysis. All the data obtained, were processed using chemometric approaches, employing the ANOVA Simultaneous Component Analysis (ASCA) algorithm, to highlight differences in metabolic profiles of specimens following exposure. An initial interesting observation is that the examined individuals showed different profiles both compared to a control group, consisting of unexposed individuals, and between the various exposure conditions. Peculiar trends were found based on the exposure site in the foundry in the case of inhalation exposure, or on the concentration of pollutants, in the case of ingestion exposure. The observed alterations mainly involve pathways related to protein synthesis, ROS scavenging mechanisms or re-balancing of the oxidative state of the organism. These conclusions are particularly interesting considering that many molecular mechanisms involved in D. melanogaster in response to considered hazards are also common to several other species, including mammals. In fact, DNA repair mechanisms, metabolic processes and the immune system of this species are significantly conserved in humans. Considering this, D. melanogaster appears as a model organism suitable for studying the effects induced by occupational exposure to PM and to evaluate possible biomarkers.